Abstract:
Amorpheae (Fabaceae: Papilionoideae) was first considered a natural group by Rupert Barneby in his illustrated monograph Daleae Imagines. Amorpheae currently comprise eight genera, ca. 250 spp., and extensive floral diversity, including loss of corolla and addition of a stemonozone. The Amorpheae and many of Barneby's subtribal groups are supported as monophyletic by previous phylogenetic analysis of nuclear ribosomal and chloroplast sequence data. However, some relationships remain unclear. A nuclear marker derived from a genomic study in Medicago, CNGC4, was sequenced in selected Amorpheae. This is one of the first applications of this marker for phylogenetic study. The new data confirm some relationships inferred using trnK and ITS, but also provide evidence for new arrangements. Combined data were used to explore several aspects of Barneby's taxonomic framework. The phylogeny, in concert with data on floral morphology, implies that simplification of the complex papilionoid flower has occurred several times in the history of the Amorpheae. © 2005, by The New York Botanical Garden Press.
PMID: 21659222;Abstract:
Phylogenetic analyses of Loasaceae that apply DNA sequence data from the plastid trnL-trnF region and matK gene in both maximum-parsimony and maximum-likelihood searches are presented. The results place subfamily Loasoideae as the sister of a subfamily Gronovioideae-Mentzelia clade. Schismocarpus is the sister of the Loasoideae-Gronovioideae-Mentzelia clade. The Schismocarpus-Loasoideae-Gronovioideae-Mentzelia clade is the sister of Eucnide. Several clades in Loasoideae receive strong support, providing insights on generic circumscription problems. Within Mentzelia, several major clades receive strong support, which clarifies relationships among previously circumscribed sections. Prior taxonomic and phylogenetic hypotheses are modeled using topology constraints in parsimony and likelihood analyses; tree lengths and likelihoods, respectively, are compared from constrained and unconstrained analyses to evaluate the relative support for various hypotheses. We use the Shimodaira-Hasegawa (SH) test to establish the significance of the differences between constrained and unconstrained topologies. The SH test rejects topologies based on hypotheses for (1) the placement of gronovioids as the sister of the rest of Loasaceae, (2) the monophyly of subfamily Mentzelioideae as well as Gronovioideae and Loasoideae, (3) the monophyly of Loasa sensu lato as circumscribed by Urban and Gilg, and (4) the monophyly of Mentzelia torreyi and Mentzelia sect. Bartonia.
PMID: 21665617;Abstract:
Comparative developmental morphology was used to assess structural homology of flowers in Dalea, Marina, and Psorothamnus of the tribe Amorpheae (Fabaceae: Papilionoideae). Dalea, Marina, and some species of Psorothamnus have an unusual petal-stamen synorganization (stemonozone) in which free petals are inserted on a region that is continuous with fused stamen filaments. Developmental studies of these three genera demonstrated similarity during organogenesis. Zonal growth results in several synorganized regions, including the stemonozone of Dalea, Marina, and some Psorothamnus. Psorothamnus species that lack a stemonozone have fused stamens and free petals inserted on the hypanthium, as in most other papilionoid legumes. We concluded that the stemonozone is not strictly homologous to either androecium or receptacle, but that it is the product of a modified androecial developmental program. In the prairie clover daleas, petaloid structures positioned between the stamens have been variously interpreted as petals or as staminodes; we infer that they have an extreme form of the daleoid stemonozone, on which five petals (no staminodes) and five stamens are inserted. Assessing structural homology of these flowers allows us to characterize accurately daleoid morphology for evolutionary studies in the tribe Amorpheae.
